19-1439; Rev 2; 4/04
SOT23, Switched-Capacitor
Voltage Inverters with Shutdown
General Description
The ultra-small MAX1719/MAX1720/MAX1721 monolithic,
CMOS charge-pump inverters accept input voltages
ranging from +1.5V to +5.5V. The MAX1720 operates at
12kHz, and the MAX1719/MAX1721 operate at 125kHz.
High efficiency, small external components, and logic-
controlled shutdown make these devices ideal for both
battery-powered and board-level voltage conversion
applications.
Oscillator control circuitry and four power MOSFET
switches are included on-chip. A typical MAX1719/
MAX1720/MAX1721 application is generating a -5V
supply from a +5V logic supply to power analog circuitry.
All three parts come in a 6-pin SOT23 package and can
deliver a continuous 25mA output current.
For pin-compatible SOT23 switched-capacitor voltage
inverters without shutdown (5-pin SOT23), see the
MAX828/MAX829 and MAX870/MAX871 data sheets. For
applications requiring more power, the MAX860/MAX861
deliver up to 50mA. For regulated outputs (up to -2 x V
IN
),
refer to the MAX868. The MAX860/MAX861 and MAX868
are available in space-saving µMAX packages.
♦
1nA Logic-Controlled Shutdown
♦
6-Pin SOT23 Package
♦
99.9% Voltage Conversion Efficiency
♦
50µA Quiescent Current (MAX1720)
♦
+1.5V to +5.5V Input Voltage Range
♦
25mA Output Current
♦
Requires Only Two 1µF Capacitors
(MAX1719/MAX1721)
Features
MAX1719/MAX1720/MAX1721
Ordering Information
PART
MAX1719EUT
TEMP RANGE
-40°C to +85°C
-40°C to +85°C
-40°C to +85°C
PIN-
PACKAGE
6 SOT23-6
6 SOT23-6
6 SOT23-6
SOT
TOP MARK
AACA
AABS
AABT
Applications
Local Negative Supply from a Positive Supply
Small LCD Panels
GaAs PA Bias Supply
Handy-Terminals, PDAs
Battery-Operated Equipment
MAX1720EUT
MAX1721EUT
Typical Operating Circuit
1µF
Pin Configuration
TOP VIEW
INPUT
1.5V to 5.5V
C1+
IN
C1-
OUT
NEGATIVE
OUTPUT
-1
·
V
IN
25mA
1µF
OUT
1
6
C1+
IN
2
MAX1721
ON
OFF
SHDN
GND
MAX1719
MAX1720
MAX1721
5
SHDN (SHDN)
C1-
3
4
GND
SOT23-6
( ) ARE FOR MAX1719
________________________________________________________________
Maxim Integrated Products
1
For pricing, delivery, and ordering information, please contact Maxim/Dallas Direct! at
1-888-629-4642, or visit Maxim’s website at www.maxim-ic.com.
SOT23, Switched-Capacitor
Voltage Inverters with Shutdown
MAX1719/MAX1720/MAX1721
ABSOLUTE MAXIMUM RATINGS
IN to GND .................................................................-0.3V to +6V
OUT to GND .............................................................-6V to +0.3V
C1+,
SHDN,
SHDN to GND .........................-0.3V to (V
IN
+ 0.3V)
C1- to GND...............................................(V
OUT
- 0.3V) to +0.3V
OUT Output Current..........................................................100mA
OUT Short Circuit to GND..............................................Indefinite
Continuous Power Dissipation (T
A
= +70°C)
6-Pin SOT23 (derate 8.7mW/°C above +70°C).................696mW
Operating Temperature Range ...........................-40°C to +85°C
Junction Temperature ......................................................+150°C
Storage Temperature Range .............................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
ELECTRICAL CHARACTERISTICS
(V
IN
= +5V, SHDN = GND (MAX1719),
SHDN
= IN (MAX1720/MAX1721), C1 = C2 = 10µF (MAX1720), C1 = C2 = 1µF
(MAX1719/MAX1721), circuit of Figure 1,
T
A
= 0°C to +85°C,
unless otherwise noted. Typical values are at T
A
= +25°C.)
PARAMETER
SYMBOL
MAX1720
R
L
= 10kΩ
MAX1719/MAX1721
R
L
= 10kΩ
T
A
= +25°C
CONDITIONS
T
A
= +25°C
T
A
= 0°C to + 85°C
T
A
= +25°C
T
A
= 0°C to + 85°C
MAX1720
MAX1719/MAX1721
MIN
1.25
1.5
1.4
1.5
50
350
0.001
0.02
7
70
99
T
A
= +25°C
T
A
= 0°C to +85°C
4
2.0
V
IN
- 0.2
0.6
0.2
-100
0.05
10
800
80
100
12
125
99.9
23
50
65
12
17
180
kHz
TYP
MAX
5.5
5.5
5.5
5.5
90
650
1
µA
µA
V
UNITS
Supply Voltage Range
V
IN
Quiescent Supply Current
(Note 3)
Shutdown Supply Current
I
CC
I
SHDN
SHDN = IN (MAX1719), T
A
= +25°C
SHDN
= GND
(MAX1720/MAX1721) T
A
= +85°C
T
A
= +25°C
I
OUT
= 0, T
A
= +25°C
MAX1720
MAX1719/MAX1721
Oscillator Frequency
Voltage Conversion Efficiency
Output Resistance (Note 1)
OUT to GND
Shutdown Resistance
SHDN/
SHDN
Input Logic High
SHDN/
SHDN
Input Logic Low
SHDN/
SHDN
Bias Current
Wake-Up Time from Shutdown
f
OSC
%
Ω
Ω
R
O
I
OUT
= 10mA
R
O
,
SHDN
SHDN = IN (MAX1719),
SHDN
= GND
(MAX1720/MAX1721), OUT is internally
forced to GND in shutdown
+2.5V
≤
V
IN
≤
+5.5V
V
IN (MIN)
≤
V
IN
≤
+2.5V
+2.5V
≤
V
IN
≤
+5.5V
V
IN (MIN)
≤
V
IN
≤
+2.5V
SHDN/
SHDN
= GND T
A
= +25°C
or V
IN
T
A
= +85°C
I
OUT
= 5mA
MAX1720
MAX1719/MAX1721
V
IH
V
IL
I
IL
, I
IH
V
V
nA
µs
2
_______________________________________________________________________________________
SOT23, Switched-Capacitor
Voltage Inverters with Shutdown
MAX1719/MAX1720/MAX1721
ELECTRICAL CHARACTERISTICS
(V
IN
= +5V, SHDN = GND (MAX1719),
SHDN
= IN (MAX1720/MAX1721), C1 = C2 = 10µF (MAX1720), C1 = C2 = 1µF
(MAX1719/MAX1721), circuit of Figure 1,
T
A
= -40°C to +85°C,
unless otherwise noted.) (Note 2)
PARAMETER
Supply Voltage Range
Quiescent Current (Note 3)
Oscillator Frequency
Voltage Conversion Efficiency
Output Resistance (Note 1)
Output Current
OUT to GND Shutdown
Resistance
SHDN/
SHDN
Input Logic High
SHDN/
SHDN
Input Logic Low
R
O
I
OUT
R
O
,
SHDN
SYMBOL
V
IN
I
CC
f
OSC
R
L
= 10kΩ
MAX1720
MAX1719/MAX1721
MAX1720
MAX1719/MAX1721
I
OUT
= 0
I
OUT
= 10mA
Continuous, long-term
SHDN = IN (MAX1719),
SHDN
= GND
(MAX1720/MAX1721), OUT is internally
forced to GND in shutdown
+2.5V
≤
V
IN
≤
+5.5V
V
IN (MIN)
≤
V
IN
≤
+2.5V
+2.5V
≤
V
IN
≤
+5.5V
V
IN (MIN)
≤
V
IN
≤
+2.5V
2.1
V
IN
- 0.2
0.6
0.2
6
60
99
65
25
12
CONDITIONS
MAX1720
MAX1719/MAX1721
MIN
1.5
1.6
TYP
MAX
5.5
5.5
100
750
21
200
UNITS
V
µA
kHz
%
Ω
mA
RMS
Ω
V
IH
V
IL
V
V
Note 1:
Capacitor contribution (ESR component plus (1/f
OSC
)
·
C) is approximately 20% of output impedance.
Note 2:
All specifications from -40°C to +85°C are guaranteed by design, not production tested.
Note 3:
The MAX1719/MAX1720/MAX1721 may draw high supply current during startup, up to the minimum operating supply voltage.
To guarantee proper startup, the input supply must be capable of delivering 90mA more than the maximum load current.
Typical Operating Characteristics
(Circuit of Figure 1, V
IN
= +5V, SHDN = GND (MAX1719),
SHDN
= IN (MAX1720/MAX1721), C1 = C2 = C3, T
A
= +25°C, unless other-
wise noted.)
OUTPUT VOLTAGE
vs. OUTPUT CURRENT
MAX1720/21toc01
MAX1720
EFFICIENCY vs. OUTPUT CURRENT
MAX1720/21toc02
MAX1719/MAX1721
EFFICIENCY vs. OUTPUT CURRENT
90
80
EFFICIENCY (%)
70
60
50
40
30
20
10
0
V
IN
= +1.5V
V
IN
= +2V
V
IN
= +3.3V
V
IN
= +5V
MAX1720/21toc03
0
V
IN
= +1.5V
-1
OUTPUT VOLTAGE (V)
V
IN
= +2V
100
90
80
EFFICIENCY (%)
70
60
50
40
30
V
IN
= +1.5V
V
IN
= +2V
V
IN
= +3.3V
V
IN
= +5V
100
-2
V
IN
= +3.3V
-3
-4
V
IN
= +5V
-5
0
5
10 15 20 25 30 35 40 45 50
OUTPUT CURRENT (mA)
20
10
0
0
5
10 15 20 25 30 35 40 45 50
OUTPUT CURRENT (mA)
0
5
10 15 20 25 30 35 40 45 50
OUTPUT CURRENT (mA)
_______________________________________________________________________________________
3
SOT23, Switched-Capacitor
Voltage Inverters with Shutdown
MAX1719/MAX1720/MAX1721
Typical Operating Characteristics (continued)
(Circuit of Figure 1, V
IN
= +5V, SHDN = GND (MAX1719),
SHDN
= IN (MAX1720/MAX1721), C1 = C2 = C3, T
A
= +25°C, unless oth-
erwise noted.)
OUTPUT RESISTANCE
vs. INPUT VOLTAGE
MAX1720/21toc04
SUPPLY CURRENT
vs. INPUT VOLTAGE
400
SUPPLY CURRENT (µA)
350
300
250
200
150
100
50
-40°C
+85°C
2.0
2.5
3.0
3.5
4.0
4.5
5.0
5.5
MAX1720
-40°C
+85°C
MAX1719/
MAX1721
MAX1720/21toc05
SHUTDOWN SUPPLY CURRENT
vs. TEMPERATURE
SHUTDOWN SUPPLY CURRENT (nA)
MAX1720/21toc06
80
70
OUTPUT RESISTANCE (Ω)
60
50
40
30
MAX1720
20
10
1.5
2.0
2.5
3.0
3.5
4.0
4.5
5.0
MAX1719/
MAX1721
450
30
25
20
15
10
5
0
-40
-15
10
35
60
V
IN
= +5V
V
IN
= +3.3V
V
IN
= +1.5V
5.5
0
1.5
85
INPUT VOLTAGE (V)
INPUT VOLTAGE (V)
TEMPERATURE (°C)
OUTPUT RESISTANCE
vs. TEMPERATURE
V
IN
= +1.5V
60
OUTPUT RESISTANCE (Ω)
50
40
V
IN
= +3.3V
30
20
10
-40
-15
10
35
60
85
TEMPERATURE (°C)
V
IN
= +5V
V
IN
= +2V
MAX1720/21toc07
PUMP FREQUENCY
vs. TEMPERATURE
MAX1720/21toc08
OUTPUT NOISE AND RIPPLE
MAX1720/21toc09
70
1000
FREQUENCY (kHz)
V
IN
= +1.5V
V
IN
= +5V
100
V
OUT
MAX1719/
MAX1721
MAX1719/MAX1721
V
OUT
MAX1720
V
IN
= +5V
V
IN
= +1.5V
10
-40
MAX1720
-15
-10
35
60
85
TEMPERATURE (°C)
10µs/div
V
IN
= 3.3V, V
OUT
= -3.17V, I
OUT
= 5mA
20mV/div, AC-COUPLED
MAX1720
START-UP FROM SHUTDOWN
MAX1720/21toc10
MAX1720
OUTPUT CURRENT vs. CAPACITANCE
MAX1720/21toc11
MAX1720
OUTPUT VOLTAGE RIPPLE
vs. CAPACITANCE
450
OUTPUT VOLTAGE RIPPLE (mVp-p)
400
350
300
250
200
150
100
50
0
V
IN
= +1.9V, V
OUT
= -1.5V
V
IN
= +4.75V, V
OUT
= -4.0V
V
IN
= +3.15V, V
OUT
= -2.5V
MAX1720/21toc12
35
V
IN
= +4.75V, V
OUT
= -4.0V
30
OUTPUT CURRENT (mA)
V
OUT
2V/div
25
V
IN
= +3.15V, V
OUT
= -2.5V
20
15
10
5
0
V
IN
= +1.9V, V
OUT
= -1.5V
500
V
SHDN
5V/div
500µs/div
R
L
= 1kΩ
0
5
10 15 20 25 30 35 40 45 50
CAPACITANCE (µF)
0
5
10
15
20
25
30
CAPACITANCE (µF)
4
_______________________________________________________________________________________
SOT23, Switched-Capacitor
Voltage Inverters with Shutdown
MAX1719/MAX1720/MAX1721
Typical Operating Characteristics (continued)
(Circuit of Figure 1, V
IN
= +5V, SHDN = GND (MAX1719),
SHDN
= IN (MAX1720/MAX1721), C1 = C2 = C3, T
A
= +25°C, unless
otherwise noted.)
MAX1721
START-UP FROM SHUTDOWN
MAX1720/21toc13
MAX1719/MAX1721
OUTPUT CURRENT vs. CAPACITANCE
MAX1720/21toc14
MAX1719/MAX1721
OUTPUT VOLTAGE RIPPLE vs. CAPACITANCE
350
300
V
IN
= +4.75V, V
OUT
= -4.0V
250
200
150
100
50
0
0
0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
CAPACITANCE (µF)
V
IN
= +3.15V, V
OUT
= -2.5V
V
IN
= +1.9V, V
OUT
= -1.5V
MAX1720/21toc15
35
30
V
OUT
2V/div
OUTPUT CURRENT (mA)
25
20
15
10
V
IN
= +1.9V, V
OUT
= -1.5V
5
0
V
IN
= +3.15V, V
OUT
= -2.5V
V
IN
= +4.75V, V
OUT
= -4.0V
400
OUTPUT VOLTAGE RIPPLE (mVp-p)
V
SHDN
5V/div
50µs/div
R
L
= 1kΩ
0
0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
CAPACITANCE (µF)
Pin Description
PIN
MAX1719
MAX1720
MAX1721
NAME
FUNCTION
1
2
3
4
5
–
6
1
2
3
4
–
5
6
OUT
IN
C1-
GND
SHDN
SHDN
C1+
Inverting Charge-Pump Output
Power-Supply Positive Voltage Input
Negative Terminal of Flying Capacitor
Ground
Noninverting Shutdown Input. Drive this pin low for normal operation; drive it high for
shutdown mode.
OUT is actively pulled to ground during shutdown.
Inverting Shutdown Input. Drive this pin high for normal operation; drive it low for
shutdown mode.
OUT is actively pulled to ground during shutdown.
Positive Terminal of Flying Capacitor
Detailed Description
The MAX1719/MAX1720/MAX1721 capacitive charge
pumps invert the voltage applied to their input. For high-
est performance, use low equivalent series resistance
(ESR) capacitors (e.g., ceramic).
During the first half-cycle, switches S2 and S4 open,
switches S1 and S3 close, and capacitor C1 charges to
the voltage at IN (Figure 2). During the second half-
cycle, S1 and S3 open, S2 and S4 close, and C1 is level
shifted downward by V
IN
volts. This connects C1 in par-
allel with the reservoir capacitor C2. If the voltage across
C2 is smaller than the voltage across C1, charge flows
from C1 to C2 until the voltage across C2 reaches
-V
IN
. The actual voltage at the output is more positive
than -V
IN
, since switches S1–S4 have resistance and the
load drains charge from C2.
_______________________________________________________________________________________
5
工业自动化与控制
京公网安备 11010802033920号
Copyright © 2005-2026 EEWORLD.com.cn, Inc. All rights reserved
电子工程世界
